Help fixing a Wharfedale amplifier

[donny0m]

Bought this amp and speaker set at a garage sale, owner said speaker dont work. I've tried out the speakers and they are great. Turns out the active subwoofer does not output signal to the speakers. The sub woofer speaker itself is going though.

I opened up the back plate to see if there was a fuse out. Only found two 6.3A fuses both intact, makes sense now because the sub is firing. There isn't any apparent damage to the circuitry and cant figure out why the speaker outputs are busted.

Any ideas on how you'd go about troubleshooting this? I have a basic understanding of electronics and have tools/multi-meter/soldering iron, etc.

 

[kellys_eye]

The active subwoofer requires an audio input signal - do you have one?

 

[73's de Edd]

Turns out the active sub woofer does not output signal to the speakers

Looking inside of the unit, I see the woofer speaker that is directly hard wired from the power output transistors .
As far as power output connections to speaker(s) . . . . are you ERRONEOUSLY thinking that the two 5 way RED and Black connectors on the back left corner are for that purpose ?
Not so . . . you have an option of feeding right and left channel audio into the unit to be blended into a mono low frequency signal into the power amp section and out into the internal speaker. You can do that by using the sets of RCA connectors on the left top corner of the rear panel.
OR you have the alternate option of using speaker impedance inputs of 4-8-16 ohm matches thru those two sets of binding posts.
Note that they are labeled as INPUTS, they are not being for power outputs .

 

[Harald Kapp]

cant figure out why the speaker outputs are busted.

Adding to @73's de Edd 's observations: There are outputs, but these are line level only (~ 1 V):

These line level outputs are probbaly active only when the line level inputs are used, not when the "speaker level inputs" are used.
In any case, you will need an additinal audio amplifier to lift the line level outputs to a level suitable for driving speakers.


The "speaker level inputs" at the bottom are used when you drive the subwoofer from the speaker outputs of an audio amplifier. You would then connect the left speaker output of the amplifier to the left speaker and to the left speaker input of the subwoofer. Same for the right side.